1. Field of the Invention
The invention relates to a wheelchair, more particularly to an improved wheel assembly for a wheelchair which requires a relatively small force to rotate the wheel assembly manually.
2. Description of the Related Art
A conventional wheelchair includes a seat portion, a pair of circular mounting plates secured respectively on two sides of the seat portion, and a pair of driven wheels. Each of the mounting plates has a fixed shaft extending therefrom, a driving unit and a gear unit which are installed on the mounting plate. Each of the driving units is driven by a rechargeable battery unit that is mounted on the corresponding mounting plate. Each of the driven wheels has a circular central portion formed with a through-hole, an annular neck flange extending from the central portion around the through hole, and an annular toothed portion formed around the flange. The flange of each of the driven wheels is sleeved rotatably on the fixed shaft of the respective mounting plate. During assembly, the annular toothed portion of each of the driven wheels is arranged to mesh with a toothed wheel of the respective gear unit so that rotation of the driving unit is transmitted to the driven wheel.
A main drawback of the conventional wheelchair is that the wheels cannot be disconnected from the gear units. Thus, the user has to exert a considerable force in order to rotate the wheels of the wheelchair whenever manual operation is desired.